Display screen or portion thereof with a graphical user interface



FIG. 1 is a front view of a display screen or portion thereof with a graphical user interface according to a first embodiment;

FIG. 2 is a front view of a display screen or portion thereof with a graphical user interface according to a second embodiment; and,

FIG. 3 is a front view of a display screen or portion thereof with a graphical user interface according to a third embodiment.

The broken lines shown in the drawings illustrate portions of a display screen or portion thereof with a graphical user interface that form no part of the claimed design. 

CLAIM We claim the ornamental design for a display screen or portion thereof with a graphical user interface, as shown and described. 